[Task] Integration-test & k8s-ingress workflows are not required checks

## Description
Branch protection (`.asf.yaml:35-37`) requires only 3 contexts (`check-license-header`, `build`, `e2e`). The `it`/`it-k8s` workflows have no `requirement` aggregation job and use `continue-on-error: true` + post-hoc shell exit — and aren't in the required list. A red `it`/`it-k8s` does not block merge.

## Location
```
.asf.yaml:35-37
.github/workflows/integrated-test.yml:174 (continue-on-error: true)
.github/workflows/integrated-test-k8s-ingress.yml:164
```

## Impact
dubbo/grpc/websocket/spring-cloud/rewrite/k8s-ingress integration regressions merge on green `build`+`e2e` alone.

## Suggested fix
Add `requirement` gate jobs (mirror `ci.yml:156-167`'s `always()` pattern) and add their contexts to `.asf.yaml`.

## Related existing issue(s)
None. #6432/#6435/#6437 are about concurrency canceling, not about missing required checks.

_Identified during the 2026-08-02 audit; full list in [`docs/issue-candidates-2026-08-02.md`](docs/issue-candidates-2026-08-02.md)._

Start with .asf.yaml:35-37 and compare the required contexts with the jobs in .github/workflows/integrated-test.yml:174 and .github/workflows/integrated-test-k8s-ingress.yml:164. Read ci.yml:156-167 for the existing always() requirement pattern. Done means both integration workflows expose requirement gate contexts, those contexts are required in .asf.yaml, and failed integration checks block merging.

Written by the indexing model from the issue text.